Background for Teachers

A physical change involves the changes that can be observed
without changing the identity of substances. A chemical change is
a process in which reactants are changed into one or more different
products. A chemical change occurs whenever compounds are formed
or decomposed. During this reaction, there is a rearrangement of
atoms that makes or breaks chemical bonds. This change is usually not
reversible.

Another way in which the distinction between chemical and
physical changes is often expressed is to state that only chemical
reactions involve the rearrangement of atoms within the molecule,
which leads to the creation of a new molecule (new substance).
Physical change does not create anything new; there is no change in
the identity of the material (substance).

Changes in state but not chemical composition are not considered
chemical changes. For example, while boiling water involves a
change in temperature and the release of a gas (water vapor), a chemical
change did not take place.

Intended Learning Outcomes

1. Use science process and thinking skills.

Instructional Procedures

Invitation to Learn

Which Soda Pop Contains the Most Fizz?

In this activity the class will be split up into five or six
different groups. Each group will be given a different brand
24 oz. bottle of soda pop. The groups will predict which soda
has the most fizz and tell why they think that. The groups will
be instructed to equally disperse about 1⁄2 of their bottle to the
members of their group using small cups. As the students drink
their soda, instruct them to think about descriptive words to
describe how the soda pop tastes. The students will write these
words on 3x5 cards. The groups will then take the remainder
of their soda in the bottle and put a balloon over the opening.
Have the students will take turns shaking the bottle lightly. The
balloon will begin to fill with carbon dioxide. Then, have the
groups will then take the carbon dioxide filled balloons and
tie them off. The groups measure their balloons on the scale
provided to see how much carbon dioxide was released from their
soda. The groups will then compare their findings.

Instructional Procedures

Hand out the Dry Ice Root Beer Recipe. Read through the recipe
with the class. (Because handling dry ice can be dangerous I
have chosen to make the root beer with the class assisting me.)
Hand out the Physical/Chemical Change Rhymes. Point out that
in the following recipe a physical change will be used to add
fizz to the root beer.

As you follow the recipe, point out to the class some facts about
dry ice. Hand out Dry Ice Facts and talk about some of the
things dry ice is used for, how it is manufactured, and what it is
made of.

When finished, put dry ice in the root beer and have the
students observe the effect. Discuss sublimation. Sublimation
is the change from solid to gas while at no point becoming a
liquid. When you place dry ice into some warm or hot water,
clouds of white fog are created. This white fog is not the CO
2
gas, but rather it is condensed water vapor mixed in with the
invisible CO
2. Also discuss that the carbon dioxide is mixing
and attaching to the liquid root beer mixture.

Ask the class: What type of a change is occurring to the root
beer mixture? A physical change is occurring. This is because
no new substances are being made, and we can easily reverse
the change. The carbon dioxide existed as a solid before we
placed it in the root beer and it exists in a gaseous form to
create fizz in our root beer.

As the dry ice sublimates in the root beer (10-15 min), take this
time to use some of your leftover dry ice chunks to do a couple
of experiments.

Popping Film Cans

A fun (and often wild) activity vividly demonstrates the
sublimation process. Place a piece of dry ice into a plastic
35mm film container - the kind that has the snap-on cap. Then
wait. The cap will pop off, and sometimes fly several meters.
The clear Fuji brand containers shoot farther than the gray and
black Kodak type. Warn anyone performing this experiment not
to aim for anyones eyes.

Singing Spoon

Press a warm spoon firmly against a chunk of dry ice. The
spoon will scream loudly as the heat of the spoon causes the
dry ice to instantly turn to gas where the two make contact. The
pressure of this gas pushes the spoon away from the dry ice,
and without contact, the dry ice stops sublimating. The spoon
falls back into contact again, and the cycle repeats. This all
happens so quickly that the spoon vibrates, causing the singing
sound you hear.

Fog Effects

When you place dry ice into some warm or hot water, clouds
of white fog are created. This white fog is not the CO
2 gas,
but rather it is condensed water vapor, mixed in with the
invisible CO
2. The extreme cold causes the water vapor to
condense into clouds. The fog is heavy, being carried by the
CO
2, and will settle to the bottom of a container, and can be
poured.

In this last step, the students will taste the root beer and write
down some of the characteristics of the root beer on the Venn
Diagram. (Focus on descriptive words and the fizz of the root
beer. I like to ask the class to rate the fizz on a 1-10 scale.)

Hand out the Yeast Root Beer Recipe to the groups. (Each of
these recipes are different from one another.) Read through
the recipe with the class, and distribute the tools needed to
make this type of root beer. It should be explained to the
students that the recipes are different to allow comparing and
contrasting. Discuss with the class that zymology is the study
of fermentation. Fermentation is the chemical conversion of
carbohydrates (sugars) into alcohols or acids. Basically, the
yeast eats the sugar and a chemical change occurs, creating
carbon dioxide. The students will then fill out their Question/
Prediction handout. The students will try to rate which root
beer recipe will have the most fizz.

I have found it more exciting to let the students follow the
recipe and make it themselves. Sometimes the students
make errors or alterations to the recipe and the outcome is
valuable in discussing the scientific process. Make sure to
rotate through the class offering help as the class follows their
recipe.

After the groups have made their root beer, make sure they
label their bottles. Then put the bottles somewhere in the
sun where they will not be disturbed for at least 4 hours.
Then chill the bottles overnight.

In this last step, have the students taste test their root beer.
Make sure the students get a chance to taste each of the root
beer recipes. Using the Venn Diagram, have the class describe
how the recipes are the same and how they are different.
Focus on descriptive words and similes and metaphors.

Extensions

Curriculum Extensions/Adaptations/
Integration

Explore zymology on the Internet/PowerPoint. What types of
jobs use zymology and what types of products are made using
zymology? Provide ideas for extension for advanced learners.

Explain and predict the effects that would occur if various
changes were made to the root beer recipes

Supply students with vocabulary and definitions.

Extend time limit for students with special needs.

Use pictures in a Power Point presentation to show the steps
of the recipe.

Include ideas for integration for other curricular areas Have
the students describe what other things taste like using similes
and metaphors.

Family Connections

Have the students take a copy of Root Beer Lady: The Dorothy
Molter Story home to read with their parents.

Have students make a list with their parents of household
products that have yeast/carbon dioxide in them. Then have
them write what characteristics the yeast/carbon dioxide has
upon the products.

Assessment Plan

Rubric: Were the objectives reached? Was Root Beer Created?

Non-Fiction Vocab-u-Write

K.W.L.

Bibliography

Instruction in 30 program areas, this paper is designed as a resource
to assist teachers in expanding and refining teaching strategies. Topics
included in the article include: activating prior knowledge, cooperative
learning, critical thinking, graphic organizers, and metacognitive
strategies.

Bathajthy, Ernest. (1988). From Metacognition to Whole Language: The Spectrum of Literacy
in Elementary School Science. 26p.

This article considers the integration of reading and writing
into elementary science. The article discusses the use of graphic
organizers for teaching text structure, and the use of semantic
feature analysis for teaching vocabulary concepts.